Recent advances in semiconductor fabrication and processing has led to increased use of electroplating to deposit a variety of materials on semiconductor devices. Such materials include electroplated copper, nickel, and tin-silver alloys. Electroplating tin-silver alloys oftentimes leads to spurious metal buildup around the lip seal and cup regions of a substrate holder assembly (sometimes implemented as a clamshell assembly). This buildup, referred to as “lip seal plating” and/or “cup bottom plating,” depending on its location, may in some circumstances cause the seal formed between the substrate and lip seal to fail, resulting in contamination of inner portions of the clamshell assembly with potentially corrosive electroplating solution.